Circadian accumulation model
A Phenomics post introduced a Diurnal Circadian Lighting Accumulation (DCLA‑CPS) model that predicts circadian phase shifts by integrating timing, duration and circadian stimulus across six schemes and reports strong validation with an R² of 0.9320 against independent studies. The post positions the model as a quantitative tool for designing lighting exposure patterns. (x.com/Phenomics_J)
Your body clock shifts when light hits your eyes at the right time, and a new model tries to predict that shift from a day’s total light exposure. (springer.com) Researchers at Fudan University tested light exposure across three time windows — 8:00 to 12:00, 13:00 to 17:00, and 18:00 to 22:00 — with 4-hour and 8-hour durations and circadian stimulus levels of 0.35 and 0.55. They tracked changes in circadian phase using the timing of minimum core body temperature, a standard marker of the internal clock. (ncbi.nlm.nih.gov) The model, called Diurnal Circadian Lighting Accumulation, adds up three things at once: when light arrives, how long it lasts, and how strongly it stimulates the circadian system. The paper says that combined measure predicted circadian phase shift with an R-squared of 0.9320 and a residual sum of squares of 0.1184 in validation against independent studies. (pubmed.ncbi.nlm.nih.gov) Circadian phase shift means moving the body’s daily schedule earlier or later, like nudging the time you get sleepy or wake up. Morning light tended to advance the clock in the experiment, while evening light tended to delay it, matching decades of chronobiology findings on light timing. (ncbi.nlm.nih.gov) The practical problem is that indoor lighting is usually designed around what people can see, measured in brightness and color, not around what the circadian system “reads” as time. The authors argue that a quantitative dose model could help plan lighting in places such as hospitals, transit settings, and other indoor environments where artificial light can shift sleep and alertness. (springer.com) The study also found that timing and duration changed the size and direction of the shift, and that spectral changes could matter even when illuminance and color temperature stayed the same. In one comparison, two lights with the same conventional settings produced different phase shifts because their circadian stimulus values differed. (ncbi.nlm.nih.gov) To build the predictor, the researchers first created a time-response curve for when light exposure happens and a dose curve for circadian stimulus, then integrated the two into a daily accumulation value. They then fit that value to phase shift with a Boltzmann function, which the paper used because circadian responses compress rather than rising without limit. (springer.com) The work was published in *Phenomics* in 2022, and the journal’s recent social post resurfaced it as a design tool rather than only a laboratory result. The paper stops short of claiming a universal prescription, but it does offer a way to turn light timing into a number that lighting designers and sleep researchers can test. (pubmed.ncbi.nlm.nih.gov)
